Tractor assemblies for perforated forms



May 2, 1967 E. ca. LIZOTTE TRACTOR ASSEMBLIES FOR PERFORATBD FORMS I Filed April 30, 1965 2 Sheets-Sheet l INVENTOR EDGAR G. LIZOTTE ATTORNEYS y 2, 1967 E. e. LIZOTTE 3,317,102

TRACTOR ASSEMBLIES FOR PERFORATED FORMS Filed April 30, 1965 2 Sheets-Sheet g Fig.5

INVENTOR EDGAR G. LIZOTTE ATTORNEYS 3,317,102 TRACTOR ASSEMBLIES FOR PERFORATED FORMS Edgar G. Lizotte, Winsted, Conm, assiguor to Royal Typewriter Company, Inc., New York, N.Y., a corporation of Delaware Filed Apr. 30, 1965, Ser. No. 452,295 Claims. (Cl. 226-75) This invention relates to tractor assemblies for moving perforated forms; more particularly it relates to tractor assemblies for moving perforated forms characterized by a belt having an endless series of flexible feed pin supporting elements so oriented and operable by control surfaces as to effect the movement of feed pins substantially at right angles to form movement into engagement with holes in and to move to forms over a straight path.

The problems of tearing or distortion of form feed holes due to inaccurate registry of pins during entry into form feed holes and creep or misalignment of the sheets of multiple sheet forms due to the expedient of making feed holes larger than the feed pin dimensions to avoid tearing; and the misalignment due to the different path lengths of top and bottom sheets of a multiple sheet form when traversing a curved path such as a platen with the resulting displacement of print work on the bottom sheet of the forms, have not been solved entirely satisfactorily by prior art tractor assemblies.

The nature of tractor assemblies of the prior art which drivingly engage and move forms over a straight portion of the forms path has required that they be mounted some distance beyond the printing line of those machines wherein type are impacted against a cylindrical platen in order that the forms path leading to the tractor assembly will be linear and free from interference with those feed pins of the tractor assembly traversing a curved path. Hence the tractor assemblies of the prior art could not be mounted coaxially with the machine platen. This shortcoming contributes to the complexity, large size and weight of prior art tractor assemblies with the result that they are expensive, and when mounted on a movable carriage they deleteriously affect carriage movement.

In accordance with the .present invention there are provided improved tractor assemblies wherein the movement of pins into and out of forms driving engagement is effected at right angles to forms movement; and engaged pins drive the forms over a linear portion of the forms path. Consequently, the pins may be substantially cylindrical with diameters substantially that of the forms holes eliminating any tendency to induce tearing or creep thereby improving registry of corresponding lines of top and bottom sheets of multiple sheet forms opposite the writing line.

The improved tractor assemblies may be employed to best advantage with machines of the type wherein a single printing element moves across the writing line inasmuch as the writing line may be located within the linear part of the forms path thereby assuring accurate registry of top and bottom sheets of multiple sheet forms.

More particularly the tractor assemblies in accordance with the invention are characterized by drive sprocket wheel supporting structure for supporting in spaced relationship, drive and idler sprocket wheels outwardly of the forms edges and by a continuous belt supported by the sprocket wheels. The belt is characterized by equispaced pin supporting elements normally converging toward a path line shorter than the path line of the belt.

The supporting structure also defines control surfaces underlying the forms edges including a straight fiat platform located between said sprocket wheels for maintaining a predetermined number of elements positioned in the path line of the belt. The control surfaces are fur- United States Patent 0 ice ther characterized by a ramp preceding and a ramp trailing the platform. The ramps are so shaped as to gradually rotate said elements about their line of connection to the belt onto and away from the platform whereby forms feed pins carried by said elements will enter into form holes substantially at right angles and drive the forms over a straight path defined by the platform. In that the normal path line of the pin supporting elements is shorter than the path line of the belt, except when traversing the ramps and platform, forms approaching the platform may traverse an arcuate path conforming to the periphery of the drive sprocket wheel without interference with forms feed pins. Accordingly, in a typewriter wherein type are impacted against a platen the drive sprocket wheel may be mounted coaxially with the platen.

An object of the invention is in the provision of compact, light-weight, low cost tractor assemblies.

Another object of the invention is to provide a tractor assembly for moving forms with a minimum of creep.

Another object of the invention is in the provision of a tractor assembly having form feed pins movable into and out of engagement with form holes at substantially right angles to form movement.

A further object of the invention is in the provision of a tractor assembly including a belt having integrally formed therewith flexible pin supporting elements normally biased from the forms path and gradually movable seriatim into and out of forms engagement during forms movement.

A still further object of the invention is to provide in combination with a tractor assembly a novel forms guide structure.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof and wherein:

FIGURE 1 is a perspective view with parts omitted showing two tractor feed assemblies for feeding forms in association with a single printing element typewriter.

FIGURE 2 is a cross sectional view taken along lines 22 of FIGURE 1 showing the left tractor assembly.

FIGURE 3 is a front elevation with parts sectioned of the right tractor assembly without the pin supporting belt;

FIGURE 4 is a cross sectional view taken along lines 4-4 of FIGURE 3; and

FIGURE 5' is a partial cross sectional view taken along lines 5-5 of FIGURE 4 showing details of the forms guide plate structure.

Referring now to the drawings wherein like reference numerals designate like or corresponding elements throughout the several views there is shown in FIGURE 1 left and right tractor assemblies generally designated by reference numerals 11L and 11R respectively adapted to drive forms 12 having feed holes 13 adjacent the edges thereof in an upward direction. The tractor assemblies are carried by a guide rod 14 extending between and secured to left and right frame members 15 and 16 respectively, and by an indexing shaft 17 rotatably mounted in and between the frame members parallel to and located below and forwardly of the guide rod 14 as most clearly illustrated in FIGURE 2. The indexing shaft is provided with a longitudinal keyway 18 to which drive sprocket wheels in the tractor assemblies are keyed, as will hereinafter appear, whereby when the index shaft is incrementally rotated, the drive sprocket wheels will be indexed accordingly. The keyed connection of the index shaft and drive sprocket wheels permit the tractor assemblies to be adjusted relative to one another to accommodate any forms width. The index shaft may be incrementally rotated in any manner. As illustrated in FIGURE 1 the left end of the index shaft may carry in one embodiment a ratchet 19 operable in association with a pawl 21 adapted when actuated manually or by power to incrementally rotate the index shaft and power the tractor assemblies.

With particular reference to FIGURES 3 and 4 each of the tractor assemblies comprises an end plate 22 secured as by screws 23 to a sprocket wheel housing and pin control block generally designated by reference numeral 24 which is preferably a molded plastic such as Delrin. The block is formed with an upper cutout 25 and a lower recess 26 adapted to accommodate respectively an idler sprocket wheel 27 and a drive sprocket wheel 28 both of which are provided about their peripheries with equispaced sprocket pins 29. The end plate is provided with an opening 31 to accommodate the guide rod 14; and the end plate and block are provided with openings 32 to accommodate the index shaft 17; the block opening 32 extending through the recess 26 whereby the drive sprocket wheel 28 may be mounted on and keyed to the index shaft by a key 33 formed interiorly of a circular opening in the drive sprocket wheel.

With further reference to FIGURE 3, the idler sprocket wheel is secured coaxially to the outer race 34 of a roller bearing 35. The inner race 36 is threaded to receive a screw 37 supported on the end plate 22, a slot 38 being provided in the end plate to permit vertical adjustment of the idler sprocket supported by the screw 37. The idler sprocket wheel is spaced from the end plate by a collar 39 whereby the idler sprocket assembly is maintained in vertical alignment with the drive sprocket wheel.

As shown in FIGURES 3 and 4, the end plate mounts a bracket 41 which supports a set screw 42 whereby the tractor feed assembly may be locked to the guide rod 14 in any lateral position.

With reference to FIGURE 1 the pin control block portions of the left and right housings extend toward one another and are formed to define pin supporting element control surfaces on the forwardly facing sides of the housings. Considering the left tractor assembly as shown in FIGURES 1 and 2, the control surfaces comprise a flat guide platform 43 on the forwardly facing side of the block between the drive and idler sprocket wheels and underlying the forms edges. As viewed in FIGURE 2 the flat guide platform is coplanar with a line tangent to the peripheries of the drive and idler sprocket wheels.

The control surfaces defined by the block further comprise planar ramps 44 and 45 respectively below and above the platform surface leading toward and away from the platform surfaces; and 'as seen in FIGURES 1 and 2 the sloping ramps extend over a path length at least as great as the spacing between form holes 13 and connect with the remaining inwardly bevelled surface 46 of the block. A groove 47 cut along the length of the platform surface extends partially into the ramps for reasons hereinafter apparent.

With reference to FIGURE 1 drive belts generally designated by reference numerals 51 are mounted on the drive and idler sprocket wheels. The belts comprise body portions 52 provided with sprocket holes 53 engageable with the sprocket pins 29 on the sprocket wheels. Joined to the body of the belts and extending laterally therefrom and overlying the control surface portions of the blocks 24 are a plurality of flat elements 54 spaced at intervals corresponding to the spacing intervals of the holes 13 in the forms to be moved.

The belts may be of any flexible material and are preferably formed of a dimensionally stable plastic and with elements 54 integral with the bodies of the belts such that the elements 54 are flexible about the line 55 4 of connection to the body of the belt and capable of fiexure also toward one another when contiguous body portions of the belt are traversing the sprocket wheels as shown in FIGURES 1 and 2.

The flexible elements 54, as best seen in FIGURE 2, normally converge inwardly such that their ends follow, considering the elements contiguous to the rear run of the belt which are not influenced by the bevelled surfaces 46, a path line shorter than the path line of the body of the belt. Each of the flexible elements 54 supports an outwardly extending substantially cylindrical drive pin 56 having a bevelled crown, the pins being adapted to enter into the form holes 13, and an inwardly extending nub 57 having a rounded crown adapted to ride the sloping ramps 44 and 45 such that the flexible elements 54 in approaching the platform are gradually rotated about the line of connection 55 to the body of the belt up to the plane of the platform as the belt is indexed, and such that the flexible elements are gradually permitted to rotate to normal position as the flexible elements leave the platform 43.

As viewed in FIGURES l and 2, those elements 54 riding the platform (three in the illustration of FIGURES l and 2) are in a path coplanar with the body of the belt and underly the forms with the drive pins 56 drivingly engaging the forms holes. As the index shaft is incrementally rotated, the nubs 57 on the elements approaching the platform ride the lower ramp 44 gradually rotating the elements into a path coplanar with the path of the belt. As hereinbefore noted the flexible elements 54 converge toward one another as contiguous portions of the belt traverse the sprocket wheels; accordingly, as they are rotated by the ramp 44, they are gradually moved apart into parallelism. Thus during approach to the platform they are moving opposite the direction of forms movement toward the trailing edges of the forms holes assuring unimpeded substantially perpendicular entry of feed pins 56 into the forms holes, minimizing any tendency to deform or tear the leading or drive edges 61 of the forms holes 13. In view of this controlled movement of the pins perpendicular to forms movement, the diameters of the pins 56 may be made substantially equivalent to the forms hole diameters assuring more accurate registry of the sheets of multiple sheet forms. As the elements 54 ride the platform associated nubs 57 extend into the groove 47 and have no control over the run of the platform 43. The action of the upper ramp which slopes at a greater angle is similar.

The above tractor assemblies as hereinbefore noted are particularly suited for mounting on a machine having a single printing element 62, as illustrated in FIGURE I, mounted on a carriage (not shown) which traverses across the forms whereby the printing line 63 may be within the straight path of the forms between sprocket wheels. The single printing element may be of the type which moves against the paper to effect an imprint, in which case the machine would be provided with a partial stationary platen (not shown) mounted between side frames 15 and 16 and located behind the paper along the line indicated by reference numeral 63, or the single printing element may be associated with a 'hammer element 64 mounted in a carriage 65 (FIGURE 4) which moves with the printing element carriage along line 63.

As viewed in FIGURE 2, in that the elements 54 are normally biased inwardly of the belt path, forms may be guided by a paper pan 66 (FIGURE 2) around the lower drive sprocket wheel without interference with the drive pins 56 on the belts thereby permitting the location of the drive sprocket wheel coaxially with a platen 67 (FIGURE 3) supported on the carriage of a fixed printing point machine which may be of the single element type or a multiple bar type.

Referring to FIGURES 3-5 there is shown associated with $1. tractor feed mechanism a forms guide device generally designated by reference numeral 68. The guide device comprises a plate 69 provided with upturned ends 71 and with an elongated slot 72 to accommodate pins 56 extending through form holes when the plate is positioned as shown in FIGURE 3 to guide and maintain engagement of the forms. The plate is formed with spaced ears 73 bent at right angles to the plate and each of the ears supports a stud 74 extending to either side of the ear. A pair of leaf springs 75 are secured at one end to the end plate and the free ends 76 thereof are bifurcated and shaped to receive the ears and partially surround the pivot studs 74 thereby biasing one or another of spaced rounded projections 77 on the extremities of the ear against the end plate, whereby the guide plates are detentably held in either the closed or open position by the leaf springs 75 as shown in FIGURE 5.

While the belts have been shown with sprocket holes in the body of the belts, the invention may utilize the spacing between the pin supporting elements to accommodate sprocket teeth adapted to drivingly engage the edges of the pin supporting elements to drive the belts.

It should be understood therefore that the foregoing disclosure relates to only a preferred embodiment of the invention and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purposes of the disclosure which do not constitute departures from the spirit and scope of the invention.

The invention claimed is:

1. In a machine of the character described, edge perforated forms feed mechanism including an endless flexible belt,

a plurality of flexible elements extending laterally from the body of said belt and normally converging inwardly of the path defined by the belt,

forms feed pins secured adjacent the ends of said elements,

a straight element guide platform located adjacent and inwardly of the upper run of said belt,

and planar ramps leading to and from said guide platform operable to gradually rotate said elements into the plane of said belt body as said belt is indexed whereby said pins will enter into forms holes near the top of said lead ramp, said guide platform maintaining said elements and associated pins in driving engagement over a straight run of the belt.

2. Apparatus as recited in claim 1 wherein said belt and elements are integrally molded of a dimensionally stable plastic material.

3. A tractor feed mechanism adapted to move forms having feed holes perforated adjacent their edges comprising in combination,

a supporting block,

an endless belt,

a plurality of flexible elements extending laterally of the body of said belt and normally converging to- 6 ward a path line shorter than the path line of said belt,

feed pins secured to the elements,

spaced sprocket wheels supported by said block for mounting and driving said belt,

and control surfaces on said block underlying the path of said elements comprising a straight fiat surface located between and in a plane tangent to the periphery of said spaced sprocket wheel adapted to maintain said elements elevated over a staight path with the pins thereon in engagement with form feed holes,

and a planar ramp surface leading up to said flat surface for gradually elevating said elements as said belt is driven whereby feed pins on said elements enter said feed holes seriatim.

4. Tractor feed mechanism for feeding edge perforated forms over a straight path comprising a pair of blocks adapted to be located on a machine adjacent the edges of forms to be printed upon,

a pair of sprocket wheels rotatably mounted in said blocks above and below a printing line,

means for indexing one of each pair of said sprocket wheels,

a flexible belt mounted on each pair of said sprocket wheels with its upper run parallel to the edge of said sheets,

a plurality of flexible elements extending laterally from said belts and normally converging below the plane of the belts and toward one another as contiguous portions of the belts traverse said sprocket Wheels,

straight guide platforms secured to said blocks and located beneath the edges of said forms adapted to maintain said elements in the plane of said belts over the upper run of said belts,

forms drive pins secured to said elements adapted to engage forms perforations and drive said forms over the run of said platforms,

and planar ramps leading onto said platforms adapted to gradually rotate said elements about their points of connection to said belts as said belts are driven whereby pins on said elements enter into forms perforations serially substantially at right angles.

5. Apparatus as recited in claim 4 wherein said blocks are movable relative to one another to accommodate different forms widths.

References Cited by the Examiner UNITED STATES PATENTS 1,875,642 9/1932 Morgan 16142 2,171,003 8/1939 Mabon 197133 2,179,156 11/1939 Mabon 226 2,703,239 3/1955 Curran et al. 22675 3,006,520 10/1961 House 22675 M. HENSON WOOD, JR., Primary Examiner.

ALLEN N. KNOWLES, Examiner. 

1. IN A MACHINE OF THE CHARACTER DESCRIBED, EDGE PERFORATED FORMS FEED MECHANISM INCLUDING AN ENDLESS FLEXIBLE BELT, A PLURALITY OF FLEXIBLE ELEMENTS EXTENDING LATERALLY FROM THE BODY OF SAID BELT AND NORMALLY CONVERGING INWARDLY OF THE PATH DEFINED BY THE BELT, FORMS FEED PINS SECURED ADJACENT THE ENDS OF SAID ELEMENTS, A STRAIGHT ELEMENT GUIDE PLATFORM LOCATED ADJACENT AND INWARDLY OF THE UPPER RUN OF SAID BELT, AND PLANAR RAMPS LEADING TO AND FROM SAID GUIDE PLATFORM OPERABLE TO GRADUALLY ROTATE SAID ELEMENTS INTO THE PLANE OF SAID BELT BODY AS SAID BELT IS INDEXED WHEREBY SAID PINS WILL ENTER INTO FORMS HOLES NEAR THE TOP OF SAID LEAD RAMP, SAID GUIDE PLATFORM MAINTAINING SAID ELEMENTS AND ASSOCIATED PINS IN DRIVING ENGAGEMENT OVER A STRAIGHT RUN OF THE BELT. 